A closer look at the advantages of conformal cooling

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The best of both worlds: Hybrid inserts

It’s therefore possible to manufacture “hybrid” inserts, where SLM is used to build on the difficult-to-cool area on top of a machined steel base. The SLM material joins with the forged steel base at the molecular level, yielding a finished tooling insert with hardened tool steel properties at a lower cost than with the SLM process alone. This solution is particularly suitable for large components and can greatly reduce costs and production time.

A successful example of the use of SLM technology is a 72-cavity mould built to make caps. The hot runner system is 992 x 602 x 229.57 mm and the moulding material is an HPDE. The moulded part has a weight of 2.2 g with a thickness of 1.2 mm. For caps and closures applications, fast cycle times and peak quality performance are required.

Related: Award-winning shop employs conformal cooling

The cavity insert, at the nozzle seat and fixed to injection point of the finished part, plays a key role. Studying the conditioning system is critical to achieving an excellent injection quality point, reduced cycle time, easier restart after downtime and scrap reduction.

With the traditional configuration of the mould, the cavity insert cooling depends on traditional drillings, holes that are compulsorily rectilinear and with a round shape. Even if accurate, they cannot be perfectly shaped to the moulded part or consistently follow the area to be cooled. SLM technology is used to overcome this limitation for a precise conformal cooling circuit in the gate injection area (with a constant distance of the channels between the nozzle seat and the molded part), and to improve the flow of the coolant.

Following the design phase, thermal and fluid-dynamic simulations were made through the use of state-of-the-art software with the aim to compare the efficiency of the cooling of the traditional type of inserts with the alternative configurations possible with SLM.

First the theoretical, followed by the practical

Once the ideal SLM configuration is identified from the thermal point of view, these analyses are followed by a structural verification to ensure the reliability of the solution along the way.

The results of the above analysis, followed by several internal tests, have shown that the use of conformal cooling allows for the reduction of the load losses of the fluid and, consequently, for the increase of the heat exchange as well as the conditioning efficiency. In this case, compared to a traditional solution, the reduction of the cycle time was about 15% without affecting the quality of the injection point.

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